For the treatment of diseases of the mucous membranes, it has proved to be useful to employ gels. On the one hand, they can be used for protecting mucous membranes as well as for keeping them moist. On the other hand, they are used to apply disinfectants and other therapeutics to the mucous membrane. These gels, which are produced from synthetic or vegetable materials and may contain various active ingredients, are applied to the mucous membranes in the nasal, oral, pharyngeal and urogenital regions.
It is a disadvantage of the known gels that they adhere only poorly to the mucous membrane, so that they do not stay sufficiently long in the location where they have been applied. Consequently, a considerably greater amount of gel must be used than would itself be necessary for an effective treatment. If not too highly viscous gels are used, these pearl off from the mucous membrane and the desired action cannot be achieved.
A further problem is the application of pharmaceutical compositions to the cornea and the conjunctiva of the human eye. In eye therapy for the treatment of diseases of the eye, gels are used which are intended to act on the cornea and the conjunctiva of the eye. The residence time of these gels on the cornea and conjunctiva, which are hereinafter, for the purpose of simplicity referred to as mucous membranes, is to last as long as possible in order to keep the eye moist, on the one hand, and to allow the active ingredients to act locally, on the other hand. In the case of the previously known compositions for the treatment of the eye, it is a problem that they do not adhere sufficiently and are washed out by the tear fluid via the tear duct. Therefore, the application must take place at shorter time intervals and with higher dosages than would be necessary if the composition adhered well, which is very unpleasant for the patient. Precisely in the case of diseases of the eye, such as the green cataract, where a continuous therapeutic treatment is necessary, it would be desirable to devise a form of application which can be used less frequently and with smaller dosages. With some other compositions the problem arises that they form a greasy film on the eye which impairs the vision. In the case of some eye diseases, for example in some cases of dry eye, a mucin deficiency develops which causes the tear fluid to wet the corneal surface insufficiently, which in turn can lead to dry spots on the cornea and to a destruction of the epithelium. Until now, no pharmaceutical composition for the improvement of this condition has been available.